In the processing of a silver halide color photographic material, used processing solutions are normally discarded as an overflow waste liquid.
However, the used processing solutions which are collected and discarded are a significant source of environmental pollution. The cost of collection and disposal of used waste processing solutions is substantial. Accordingly, if the used processing solutions (i.e., overflow waste liquids) can be reused as a replenisher, the above described problems can be eliminated. Furthermore, effective components remaining in the overflow waste liquids are also potentially reused. Accordingly, the required amount and cost of fresh replenisher chemicals would be further reduced. Therefore, many regeneration studies have been conducted in an effort to enable the reuse of used processing solutions by accommodating for the fluctuation in the processing solution caused by the processing, namely, by removing accumulated components that adversely affect the photographic properties and by adjusting for the reduction in activity caused by consumption of the processing solution components.
In particular, the process for the color development of a color photographic material yields a highly alkaline aqueous waste which results in substantial organic contamination represented by BOD (biochemical oxygen demand). Furthermore, the color development process requires expensive chemicals. Consequently, various approaches have been proposed with respect to chemical conservation and waste reduction for the color development process.
As described above, the regeneration normally requires the removal of accumulated components harmful to photographic properties and the replenishment of active components consumed by the process. In particular, means for removal of accumulated harmful components has been investigated. In the color development, an area of great interest has been the removal of bromide ion eluted from the light-sensitive material which strongly inhibits development. For example, an approach for regeneration utilizing electrodialysis is proposed in JP-A-51-85722, JP-A-54-37731, JP-A-56-1049, JP-A-56-27142, JP-A-56-33644 and JP-A-56-149036 (the term "JP-A" as used herein means an "unexamined published Japanese patent application"), and JP-B-61-10199 and JP-B-61-52459 (the term "JP-B" as used herein means an "examined Japanese patent publication"). In addition, other various approaches for the regeneration of color developers have been proposed. JP-B-55-1571 and JP-A-58-14831 propose the utilization of activated carbon. JP-A-52-105820 propose the utilization of ion exchange membranes. JP-A-55-144240, JP-A-53-132343, JP-A-57-146249, and JP-A-61-95352 propose the utilization of ion exchange resins.
However, the above described approaches require the analysis of the developer in order to control the composition of the developer. Thus, a highly precise control technique and expensive apparatus is also required. Accordingly, analysis and control techniques have been employed in some large scale processing laboratories.
On the other hand, another approach has been proposed which does not employ an analysis and control technique. In this approach, the composition of the replenisher of the color developer (color developer replenisher) is controlled to reduce the replenishment rate. In the above-described low replenishment process, the control of the composition of the replenisher is accomplished by, e.g., concentrating the components of the replenisher that are consumed such as the color developing agent and preservative, such that the required amounts of the replenishment components are supplied using a reduced replenishment rate. When a silver halide color photographic material is processed, halogen ions are released into the color developer. In the low replenishment process, this causes a rise in bromide ion concentration in the color developer, inhibiting development. Accordingly, in order to reverse this phenomenon, various approaches have been proposed. For example, the bromide concentration in the replenisher is generally reduced from that employed in the ordinary replenishment process.
Further approaches have been proposed in JP-A-61-70552, JP-A-63-106655, and JP-A-1-105948. In these approaches, a silver halide photographic material having a high silver chloride content is used to reduce the accumulation of bromide ion released into the color developer, to thereby also reduce the replenishment rate. Alternatively, the replenishment rate is reduced to an extent that the replenishment does not overflow the processing tank.
The low replenishment process using a silver halide photographic material having a high silver chloride content is advantageous in that large scale facilities are not required. However, the low replenishment process requires the concentration of the replenisher to supply the required amount of essential components as described above. The low replenishment process is therefore disadvantageous in that developing agents, fluorescent brightening agents and preservatives are easily crystallized and the replenishment precision is degraded, to thereby result in fluctuation of photographic properties.
After considering the above-described problems, the present inventors have conducted extensive studies to provide a remarkably improved regeneration process which eliminates of the necessity of large scale regeneration apparatus and overcomes problems caused by the concentration of the replenisher, by using only a silver halide photographic material having a high silver chloride content and by compensating for the consumption of essential components without removing halides from the used color developer. After further studies, the present inventors have found that in the development of a light-sensitive material, as the regeneration is repeated time after time, a fluctuation in photographic properties results, thereby making it difficult to obtain fully satisfactory results. In particular, the resulting photographic properties were found to vary with the amount of light-sensitive material being processed per unit time. More particularly, if the amount of light-sensitive material being processed is small, a reduction in sensitivity and high contrast results. On the other hand, if the amount of the light-sensitive material being processed is large, a rise in sensitivity and low contrast results.